This invention relates generally to ring binder mechanisms for retaining loose-leaf pages, and more specifically to a ring binder mechanism having a hinge plate that slides for unlocking ring members mounted thereon and pivots for moving them to an opened position.
A typical ring binder mechanism retains loose-leaf pages, such as hole-punched papers, in a file or notebook. It generally features multiple rings, each including two half ring members that mount on two adjacent hinge plates. The hinge plates join together about a pivot axis and pivot within an elongated housing, allowing the ring members mounted thereon to move between an opened position where pages may be added or removed, and a closed position where pages are retained and can move along the rings. An operator may typically open or close the ring members by manually pulling the ring members apart or pushing them together. In addition, in some mechanisms the operator can move a lever located at one or both ends of the mechanism to open or close the ring members.
The paired ring members of these known mechanisms often have free ends with tip formations that do not always exactly align when the ring members are closed, and misalignment of the ring members in directions transverse to longitudinal centerlines of the ring members is common. Moreover, even if alignment is initially perfect upon closure, the free ends may still be able to move relative to each other. Accordingly, pages bound by these known mechanisms may not smoothly move from one ring member to the other and may be torn.
It is known to provide paired ring members that have free ends with interlocking tip formations to hold the paired ring members in alignment when they are closed. Examples are shown in U.S. Pat. No. 5,660,490 (Warrington) and U.S. Pat. No. 6,293,722 (Holbrook et al.) and in U.S. Pat. Publ. No. 2006/0153628 (Tanaka et al.). To open these ring members, the interlocking formations must first be disengaged. This is typically accomplished by moving one of the ring members in a direction parallel to a longitudinal axis of the housing relative to the paired ring member. In U.S. Pat. No. 5,660,490 the ring members themselves are flexed in opposite longitudinal directions to disengage the interlocking tip formations. But the ring members can be difficult to manually flex, and they may bend or fatigue and impair accurate alignment. In U.S. Pat. No. 6,293,722 the ring members of each ring are formed as ring assemblies. One of the ring assemblies is mounted on a sliding structure for moving the ring members in a longitudinal direction to disengage the interlocking tip formations. But the complex structures associated with moving ring members in a longitudinal direction can be cost prohibitive for mass producing the mechanisms. In U.S. Pat. Publ. No. 2006/0153628 the ring members are mounted on hinge plates, and the hinge plates slide in opposite longitudinal directions to disengage the interlocking tip formations. But direct manipulation of the ring members as required here often requires two hands to disengage the interlocking tip formations. It would therefore be desirable to provide a ring binder mechanism with locking ring members that is easy to manufacture, simple to use, and durable.